Baseboard heater



1967 M. o. WILHOITE 3,348,533

BASEBOARD HEATER Filed June 23, 1965 3 Sheets-Sheet l ATTORNEYJ Oct.'24,19 M. o. WILHOITE [BASEBQARD HEATER 3 Sheets-Sheet 2 Filed June 23, 1965INVENIOR} flame/9x 0. M4 1 /0/75 ATTORNEYS Oct- 1 I M. o. .wlLHO lTE3,348,533 7 BASEBOARD HEATER Filed June 23, 1965 3 Sheets-Sheet 5INVENTOR ATTORNEY 5 United States Patent 3,348,533 BASEBOARD HEATERMurray 0. Wilhoite, Nashville, Tenn., assignor to Temco, Inc.,Nashville, Team, a corporation of Tennessee Filed June 23, 1965, Ser.No. 466,370 2 Claims. (Cl. 12690) This invention relates to sealed gasfired space heaters and in particular to a sealed combustion chamber foruse in such a heater.

It is the primary object of the present invention to provide anelongated sealed combustion unit suitable for use in a gas firedbaseboard heater,.the combustion unit being of improved construction toprovide more eflicient burning of the fuel.

It is a more specific object to provide an elongated gas combustion unitof the above type whose inner contours and baflle arrangement effect aneven flow of exhaust gases along the length of the unit toward a centralexhaust gas vent. The improved construction also limits recirculatingmovement of gases at the ends of the unit in a manner to prevent blowingout of the burner flame at the ends of the unit.

The invention will be further understood from the following detaileddescription taken with the drawings in which:

FIGURE 1 is a simplified perspective view of a gas fired baseboardheater in a partially disassembled condition;

FIGURE 2 is a vertical transverse sectional view taken through themiddle of the heater of FIGURE 1;

FIGURE 3 is a front elevational view of the combustion unit of FIGURE 1;

FIGURE 4 is a-rear elevational view of the combustion unit of FIGURE 1;

FIGURE 5 is an end elevational view of the combustion unit of FIGURE Iviewed from the right;

FIGURE 6 is a sectional view taken on the line 6-6 of FIGURE 4; and

FIGURE 7 is a fragmentary perspective view of the end of the combustionunit viewed from the left.

Referring to FIGURE 1 there is shown a baseboard heater 10* including asits major elements an open front cabinet or casing 12, a sealedcombustion unit 14 embodying the principles of the present invention andsuitable automatic controls 16 for the flow of fuel gas to thecombustion unit 14. The casing 12 may be of any suitable constructionand as shown includes a rear wall 18, a bottom wall 20, end walls 22 and24 and a narrow top wall 25. The rear wall 18 is positioned against anexterior wall 26 of a building, and the bottom wall 20 rests on thefloor 27. In a completely assembled installation, as shown in FIGURE 2,there is also provided a front panel 28 which is releasably secured inplace. The panel 28 is imperforate along its entire central horizontalportion 28a and is of open or louvred construction above and below thecentral portion 28a.

Directly behind the imperforate panel portion 28a and spaced apart fromthe panel 28 and the combustion unit 14 is a vertical heat shield 30'which has substantially the same length and width as the imperforatepanel portion 28a. A rear heat shield 32 of inverted L shape is providedbetween a vertical partition 33 and the combustion unit 14, thehorizontal portion of the L overlying the combustion unit 14 in spacedapart relationship. The top and ends of the casing are sealed to thewall 26 with a gasket 31. The combustion unit 14 is constructed of twopressed metal plates 34 and 36 having their edges secured together as bywelding to form an outwardly projecting circumscribing flange 38 on theunit 14. The

rear plate 34 is provided with four equi-spaced air inlet holes 40disposed in a row along the lower part of the ICC plate, each hole 40being of elongated shape as seen in FIGURE 4. The front plate 36 isprovided with a single elongated aperture 42 which in a completeinstallation is covered with a removable inspection plate 44 (FIGURE 2)and cooperating gasket 46.

An exhaust outlet opening 48 is located in the upper part of thecombustion unit 14 on a vertical median line. As seen in FIGURES 2 and 4the outlet opening 48 is provided in the rear plate 34 and is surroundedlaterally with a rearwardly projecting flue collar 49. The collar 49 isconstructed of a rear tubular part 50 of circular cross section and aforward tapered tubular part 52 which is welded to the plate 34 alongthe periphery of the opening 48. Each of the parts 50 and 52 has aradially outwardly projecting flange, and the flanges are weldedtogether to form a rigid circumferential flange'54 intermediate the endsof the collar 49. In an assembled heater the rear part 50 of the collar49 extends through the vertical partition 33 into communication with ahorizontal flue 58, and the rear face of the flange 54 is sealed to thefront of the partition 33 with a gasket 60.

Referring more specifically to the construction of the combustion unit14 it will be seen that the contours of the front and rear plates 36 and34 provide an enlarged lower chamber 62, an enlarged upper chamber 64each of which extends substantially the length of the unit 14 andanintermediate restricted chamber 66 providing communication between theother two chambers.

A straight burner tube 68 is disposed adjacent the air inlet openings 40and extends substantially the entire length of the chamber 62. The leftend of the burner tube 68, as viewed from the front, is closed and theright end is open for receiving asupply of gas from a suitableconnection (not shown), the latter being mounted on a plate 69 (FIGURE5) secured to the end of the unit. The burner tube is supported by meansof end brackets 68a and 68b which are welded to the inner surfaces ofthe chamber 62. The upper surface of the tube 68 is provided with alarge number of gas openings 70 whereby in operation a flame will occupymost of the space within the chamber 62.

As seen in FIGURES 2, 5 and 6, the chamber 62 in cross section is shapedthroughout its length generally as an inverted isosceles triangle, theupper limit thereof being defined by the restricted chamber 66. Thejunction between these two chambers 62 and 66 occurs along generallyhorizontal portions of the plates 34 and 36- identified at 72 and 74 inthe drawings.

The upper or exhaust chamber 64 within the combustion unit 14 extendssubstantially the entire length of the combustion unit 14 and has across sectional shape of gradually increasing area from the ends towardthe middle. The front to rear dimension, or thickness of the chamber 64is constant throughout its length, and the increasing cross section iseffected by two inclined walls 76 and 7 8 on the front plate 36 and twocorresponding inclined walls 80 and 82 on the rear plate 34. Thegreatest vertical dimension of the exhaust chamber 64 occurs at theintersections of the wall 76 with wall 78 and the wall 80 with wall 82,the exhaust outlet opening 48 being disposed at this location. Theremainder of the chamber 64 is defined by horizontal flat plate portions84, 86 and by vertical flat plate portions 88 and 90, the latterportions being generally triangular and defining, respectively, thefront and back walls of the chamber 64.

As best shown in FIGURES 6 and 7, the intermediate restricted chamber 66is formed of outwardly bulging portions of the plates 34 and 36, thebulges defining a lower chamber section 66a and an upper chamber section66b. The lower section 66a communicates directly with the upper end ofthe flame chamber 62. In an upward direction the front to rear dimensionof the section 66a de- 3 creases due to the inwardly curving shape ofthe plates 34 and 36 in this area. As seen in FIGURES 3 and 7 thesection 66a has a uniform vertical dimension along its length. The upperchamber 66b, on the other hand, is of uniform front to rear dimension,or thickness, along its length and of varying vertical dimension. Thevarying vertical dimension is effected by the inclined walls 76, 78, 80and '82 as seen, for example, in FIGURES 6 and 7. Rigidity is importedto the section 66b by two indentations in the walls thereof whichproject inwardly into contact with each other as at 92 (FIGURES 2 and7). It will be seen, then, that the section 66b is in the form of arather narrow slot which provides communication between the upper, orexhaust chamber 64 and the chamber section 66a.

It will be seen in FIGURES 1, 3 and 4 that the ends of the chambersections 66a and 66b terminate short of the ends of the exhaust chamber64 and the flame chamber 62 and differ from each other in shape. Thearrangement together with an internal recirculation baflle 94 at one endis designed to achieve uniform flow of exhaust gases upwardly andcentrally toward the flue collar 49. As best seen in FIGURES 1, 3 and 7,the left end of the chamber 66 as viewed from the front is wing-shapedin that the front plate 36 has inclined walls 96 and 9 8 which intersecteach other at the junction of the chamber section 661) with the chambersection 66a. The wall 96 slopes downwardly and centrally from the end ofthe wall 76, the latter defining the bottom of the exhaust chamber 64.The wall 98 slopes upwardly and centrally from a location spaced fromthe end of the top wall 72 of the flame chamber 62. The rear plate 34has corresponding inclined Walls 100 and 102 which, as seen in FIGURE 3,are the mirror images of the walls 96 and 98.

The right end of the restricted chamber 66 as viewed from the front isdefined by inclined walls 104 and 106 on the front plate 36, as seen inFIGURES 1 and 3. These walls lie in substantially the same plane andslope upwardly and centrally from a location spaced from the end of thelower chamber 62 to a location spaced from the end of the exhaustchamber 64. As seen in FIGURE 4, the rear plate 34 is provided withinclined walls 108 and 110 which are the mirror images of the walls 104and 106, respectively.

Still referring to the right end of the restricted chamber 66 it will beseen in FIGURES 3, 4 and 6 that the recirculation baflie 94 is agenerally L-shaped member dis? posed so as to extend across thefront-to-rear dimension of the chamber 66a. The baffle includes ahorizontal leg portion 94a located in the plane of the junction betweenthe lower chamber 62 and the chamber section 66a and an upwardlyextending leg portion 94b which projects into the chamber section 66a.The edges of the horizontal portion 94a extend beyond the width of theupstanding portion 94b and are secured as by welding to the innersurfaces of the walls 72 and 74 as seen in FIGURE 6. The upstandingportion is spaced from the inclined walls 106 and 110 and slopesslightly toward the center of the heating unit 14. The free upper edgeof the upstanding portion 94b terminates slightly below the junction ofthe chamber section 66a with the chamber section 66b. As seen in FIGURE3, that portion of the burner tube 68 directly below the bafiie 94 isnot provided with gas apertures.

The construction of the flue 58 and related parts is shown in FIGURE 2and is of the type fully disclosed in Nordholt et al. Patent 2,964,034.The rear end of the flue collar 49 fits tightly into the flue 58 whichis a cylindrical conduit passing horizontally through a hole cut in thebuilding wall 26 and defining therewith an annular air inlet passage111. The outer end of the flue 58 is fitted with a dish-shaped member112 having a central aperture defined by an inturned flange 114, thelatter engaging the flue 58. Outwardly of the member 112 are twocentrally apertured spaced-apart baflies 116 and 118 and an end plate1-20. The baflles and end plate together with an annular plate 122 areassembled by means of tubular spacer members 124 and rivets 126. Acylindrical air inlet screen 128 ececntrically surrounds that portion ofthe vent 58 which is disposed outside the building wall 26 and issupported at one end by a flange 130 on the plate 122 and at the otherend by an annular mounting plate 132, the latter being secured to theexterior surface of the building Wall 26.

The rear wall 18 of the heater casing 12 is provided with central airinlet opening 133 having a flanged periphery 134 which engages theperiphery of the hole in the building wall 26. There is thereby providedcommunication between the annular air inlet passage 111 and a chamber136 defined by the rear wall 18 and the vertical partition 33. AnL-shaped baflie 138 secured to the partition 33 is disposed in thechamber 136 along the top of the opening 133 to direct incoming airdownwardly. A series of connecting pipes 140 place the bottom of thechamber 136 in communication with the air inlet holes 40 in thecombustion unit 14. The rear end of each of the pipes 140 passes throughthe partition 33 and is sealed thereto by a flange 142 and gasket 144.The forward end of each of the pipes 140 is sealed to the periphery ofone of the air inlet holes 40 by a gasket 146.

In operation of the heater 10, assuming that fuel gas is being deliveredto the burner tube 68 and burned just I above the apertures 70 in thechamber 62, combustion gases pass upwardly through the intermediatechamber 66 into the exhaust chamber 64. The gases flow from the ends ofthe chamber 64 toward its center, then rearwardly into the flue collar49 and then into the flue 58. The rear end arrangement of the latterdischarges the combustion gases in a radial direction between thebafiles 116 and 118, the latter together with the end cap and thedish-shaped member 112 preventing variations of exhaust flow withchanges in external wind conditions.

The draft created by the flow of combustion gases draws outside airthrough the passage 111 into the chamber 136 and thence through theconnecting pipes into the combustion unit by way of the holes 40.

The air within the heater casing 12 becomes heated by contact with theexterior surfaces of the combustion unit 14 and rises so as to flowthrough the upper part of the front panel 28 after having been directedforwardly by the baflie 32. Room air is simultaneously drawn rearwardlyinto the casing 12 through the lower part of the front panel 28.

It will be appreciated that the elongated shape of the com-bustion unit,for example 4 /2 feet long by 9 inches tall by 2 /2 inches maximumthickness, presents opportunities for the creation of stagnant zones andunpredictable recirculation currents either of which reduces theefliciency of the unit. The primary concern of the present invention isthe configuration of the unit '14 which achieves uniform burning of thegas and continuous free flow of the incoming fresh air and outgoingcombustion gases. One feature which is of importance is the shape of theexhaust chamber 64 which increases in cross sectional area from thecenter toward its ends. This has the effect of equalizing the rate ofcombustion gas flow at the center and ends of the chamber. The gasestend to flow more rapidly through the smaller cross sections at the endsand thereby move quickly toward the flue collar 49, whereas the gasesnear the center have a lesser distance to travel to reach the collar andcan move more slowly through the greater cross section at this location.

Another feature which aids in efiicient operation is the shape and endconstruction of the intermediate chamber 66. This chamber is purposelymade of restricted cross section relative to the other chambers 62 and64 because this construction is effective in reducing the shortcircuiting of combustion gas from the upper chamber 64 back' into thelower chamber 62. Recirculation of this type is especially likely tooccur in an elongated combustion unit and tends to blow out the flame atthe ends of the burner tube. It has been found that in addition to therestricted cross section it is desirable to provide the baffle 94 abovethe gas inlet end of the burner tube to further reduce recirculation.The shape of the ends of the restricted chamber 66 is also importantfrom this standpoint.

While a specific embodiment has been described and illustrated by way ofexample, the invention is not limited to the details thereof except asthey appear in the appended claims.

What is claimed is:

1. A gas-fired horizontally elongated combustion unit for a spaceheater, the length of said unit being substantially greater than thevertical and transverse dimensions, said unit having walls definingthree elongated chambers extending longitudinally of said unit anddisposed one above the other, the lowermost chamber having a generallyuniform transverse cross sectional area along its length andcommunicating along its length with the bottom of the intermediatechamber, said lowermost chamber having at least one air inlet openingtherein and carrying an elongated gas burner tube which extendssubstantially the length of said lowermost chamber, the uppermostchamber having a vertical dimension which increases from each end towardthe middle thereby efiecting a transverse cross sectional area which isgreatest at the middle, the wall at the location of greatest verticaldimension having a horizontally facing combustion gas outlet opening,said intermediate chamber being of lesser length and lesser transversedimension than said lowermost chamber and said uppermost chamber, saidintermediate chamber tapering upwardly and inwardly toward thelongitudinal center line of said unit thereby forming a slot ofrelatively small width extending the length of said intermediatechamber, said slot communicating along its length with the bottom ofsaid uppermost chamber, said gas burner tube being sealed at one end andopen at the other end to receive gas, the wall of said unit whichdefines the end of said intermediate chamber remote from the open end ofthe burner tube being inclined upwardly and inwardly toward thetransverse center line of said unit from the bottom of said intermediatechamber to the lowermost edge of said slot and then inclined upwardlyand outwardly away from said transverse center line, said -unit furthercomprising a small generally L-shaped baflle disposed in saidintermediate chamber near the open end of said gas burner tube, saidbaflle having a horizontal leg portion blocking communication betweensaid intermediate chamber and said lowermost chamber, said baffle havingan upstanding portion remote from the open end of said burner tube.

2. A gas-fired combustion unit for a space heater, said unit beingdefined by front and rear walls sealed to each other along their edgesand defining between them a lower longitudinally extending chambercarryingwithin it an elongated gas burner tube, an intermediate chambercommunicating along its length with said lower chamber, saidintermediate chamber being parallel to and spaced closely above saidlower chamber and said burner tube and being of lesser length than saidlower chamber, both ends of said intermediate chamber terminatinglongitudinally inwardly of the corresponding ends of said lower chamber,and an upper chamber communicating along its length with saidintermediate chamber, said upper chamber being substantially coextensivewith said lower chamber and extending longitudinally beyond both ends ofsaid intermediate chamber, an end of said intermediate chamber beingdefined by two inclined end walls one of which extends upwardly andlongitudinally inwardly from the junction of said intermediate chamberwith said lower chamber and the other of which extends downwardly andlongitudinally inwardly from the junction of said intermediate chamberwith said upper chamber and merges with said first-mentioned end wall,whereby said inclined end walls lie closely adjacent the correspondingend of said burner tube so that said one other end wall prevents anyappreciable recirculation of combustion gases downwardly toward saidtube.

References Cited UNITED STATES PATENTS 3,058,457 10/1962 Fiedler 126-913,234,930 2/1966 Hodges 12690 FREDERICK KETTERER, Primary Examiner.

1. A GAS-FIRED HORIZONTALLY ELONGATED COMBUSTION UNIT FOR A SPACEHEATER, THE LENGTH OF SAID UNIT BEING SUBSTANTIALLY GREATER THAN THEVERTICAL AND TRANSVERSE DIMENSIONS, SAID UNIT HAVING WALLS DEFININGTHREE ELONGATED CHAMBERS EXTENDING LONGITUDINALLY OF SAID UNIT ANDDISPOSED ONE ABOVE THE OTHER, THE LOWERMOST CHAMBER HAVING A GENERALLYUNIFORM TRANSVERSE CROSS SECTIONAL AREA ALONG ITS LENGTH ANDCOMMUNICTING ALONG ITS LENGTH WITH THE BOTTOM OF THE INTERMEDIATECHAMBER, SAID LOWERMOST CHAMBER HAVING AT LEAST ONE AIR INLET OPENINGTHEREIN AND CARRYING AN ELONGATED GAS BURNER TUBE WHICH EXTENDSSUBSTANTIALLY THE LENGTH OF SAID LOWERMOST CHAMBER, THE UPPERMOSTCHAMBER HAVING A VERTICAL DIMENSION WHICH INCREASES FROM EACH END TOWARDTHE MIDDLE THEREBY EFFECTING A TRANSVERSE CROSS SECTIONAL AREA WHICH ISGREATEST AT THE MIDDLE, THE WALL AT THE LOCATION OF GREATEST VERTICALDIMENSION HAVING A HORIZONTALLY FACING COMBUSTION GAS OUTLET OPENING,SAID INTERMEDIATE CHAMBER BEING OF LESSER LENGTH AND LESSER TRANSVERSEDIMENSION THAN SAID LOWERMOST CHAMBER AND SAID UPPERMOST CHAMBER, SAIDINTERMEDIATE CHAMBER TAPERING UPWARDLY AND INWARDLY TOWARD THELONGITUDINAL CENTER LINE OF SAID UNIT THEREBY FORMING A SLOT OFRELATIVELY SMALL WIDTH EXTENDING THE LENGTH OF SAID INTERMEDIATECHAMBER, SAID SLOT COMMUNICATING ALONG ITS LENGTH WITH THE BOTOM OF SAIDUPPERMOST CHAMBER, SAID GAS BURNER TUBE BEING SEALED AT ONE END AND OPENAT THE OTHER END TO RECEIVE GAS, THE WALL OF SAID UNIT WHICH DEFINES THEEND OF SAID INTERMEDIATE CHAMBER REMOTE FROM THE OPEN END OF THE BURNERTUBE BEING INCLINED UPWRADLY AND INWARDLY TOWARD THE TRANSVERSE CENTERLINE OF SAID UNIT FROM THE BOTTOM OF SAID INTERMEDIATE CHAMBER TO THELOWERMOST EDGE OF SAID SLOT AND THEN INCLINED UPWARDLY AND OUTWARDLYAWAY FROM SAID TRANSVERSE CENTER LINE, SAID UNIT FURTHER COMPRISING ASMALL GENERALLY L-SHAPED BAFLE DISPOSED IN SAID INTERMEDIATE CHAMBERNEAR THE OPEN END OF SAID GAS BURNER TUBE, SAID BAFFLE HAVING AHORIZONTAL LEG PORTION BLOCKING COMMUNICATION BETWEEN SAID INTERMEDIATECHAMBER AND SAID LOWERMOST CHAMBER, SAID BAFFLE HAVING AN UPSTANDINGPORTION REMOTE FROM THE OPEN END OF SAID BURNER TUBE.